A structure which has a waterproof layer made of a polyurethane-based resin, a polyurethane based resin, Fiber Reinforced Plastics (hereinafter, refer to FRP) or the like, and an inorganic material layer which is made of mortar, concrete or the like and is cast on the waterproof layer, has been provided in an underground street, a subway station, an underground garage, an underground city or the like, or roofs of such subsurface structures.
Such a structure is made by forming a waterproof layer made of a polyurethane based resin or the like and forming an inorganic material layer on the waterproof layer.
When the inorganic material was cast on the waterproof layer, a rubber asphalt sheet was adhered thereto or a resin mortar or an appropriate primer was applied to the waterproof layer, in order to improve adhesion strength between the waterproof layer and the inorganic material layer (see Japanese Unexamined Patent Application, First Publication No. 2002-364297).